Cut and paste the quote from the book, the dimwitted doesn't read well.
"The Aryans first settled along the Indus river in the same place, where the Harappan people had lived. During the early part of their arrival, and for a period, they mixed and inter-married with the local Indian people who were predominantly Dravidians. The Aryans continued to live there from about 1500 to 800 BCE.
The Caste-system in India started during the same period. Around 800 BCE, the Aryans learned the use of Irons for making tools and weapons, probably from the people of West Asia, the Assyrians who had learned it from Indo-European Hittites. With the new iron weapons, t
he Aryan conquered (Invade) and overran the territories up to the Ganges River Valley and established new settlements there. After their move into the Ganges Valley, the Aryans were very far from West Asia and had much less contact with the West Asian people. They began to mix more with the Indian people, and their gods also got mixed up with the native Indian gods.
The Aryan conquest of the Ganges is narrated in the Mahabharata, dated around 800 BCE. However, the Aryans did not advance any further into India. At that time, South India was ruled by different Dravidian kings who were independent of the Aryans. Stories of fights between the Aryans & the Southern Dravidians are told in the Ramayana. Sati, the first wife of Shiva, is supposed to have immolated by burning, because her Dravidians relations ill-treated their Aryan son-in law."
Invasion of the Genes Genetic Heritage of India - B. S. Ahloowalia - Google Buku